1. Technical Field of the Invention
The present invention is directed to a process and apparatus for the production of pile-up lids, and to a pile-up lid.
2. Prior Art
Conventional lids are generally formed by a perimetric element, apt to be positioned on the outside edge of a container to be closed, and by an upper wall closing the perimetric element.
With regard to a particular structure of lid, generally circular in shape, of the kind, for example, that is used in the ice cream containers and the like, it is formed by a ring-shaped element at the top of which a disk is inserted to close the upper opening of the container, which disk has its circumference edge folded upwards, on which edge the upper edge of said ring-shaped element is in turn folded over and fixed. In this way a stable complex is formed.
Furthermore, in this type of lid, a ring-shaped bead is formed around the circumference of the surface of said ring-shaped element, said bead having the function of creating a snap-on engagement with the protruding edge of the associated container at its top.
However, these known lids have the disadvantage that they cannot be piled up one on top of another because, due to their shape, the diameters of the top and bottom edges of the lids are identical.
This creates a number of problems during storage and transport, as said lids must be stored in large containers, generally plastic bags, and must be inserted into the inside thereof loose, with a consequent great deal of space. Furthermore, when stored in this way they are subject to knocks, folding, breakage and generally, due to the possibility of free movement within the packing, to rubbing, which can result in deterioration of the surface appearance and flatness thereof.
Furthermore, the above conditions cause a number of problems for the operator when removing said lids from their packing for loading them, in a pile, into the operating machine in order to carry out their insertion onto the relative containers the results in considerable loss of time.
The object of the present invention is therefore to provide a lid that eliminates the problems described above, giving a surprising simplification of the operation of storage and transport of said lids, as well as their loading into the operating machine by the operator, with a considerable reduction of the storage space and time required and consequently improved productivity.
A further object of the present invention is to provide a pile-up lid produced by the process described below.
According to the present invention, a process is therefore provided for the production of pile-up lids, each of which is formed by a closing upper wall and by an element arranged around the perimeter of said upper wall and which forms a lip protruding above said upper wall, and a skirt extending below said upper wall;
the process being characterized by the following steps:
positioning a lid on a supporting element;
bringing said supporting element near an area in a first frame that is delimited by a plurality of first external sector elements and by a plurality of second internal sector elements, until it comes into contact with said plurality of first and second sector elements, said first and second sector elements having respective indentations on the respective contact surfaces; and
bringing said first external sector elements and said second internal sector elements together in synchrony in radially opposite directions, said first and second sector elements being movable on the same plane in such a way that, owing to the forced approach of said contact surfaces of the first and second sector elements with said upper lip of said lid inserted between them, a reeding pressure moulding is achieved on both the external and the internal surfaces of said upper lip, so as to give said lip a reduced perimeter outline apt to allow piling up on other similar lids, after extraction of the lid from said supporting element.
The present invention also provides an apparatus for carrying out the above process, characterized by that it comprises:
a first frame;
a plurality of first external sector elements slidingly arranged in said first frame;
first return elastic means for said plurality of first external sector elements;
a plurality of second internal sector elements slidingly arranged in said first frame;
second return elastic means for said plurality of second internal sector elements;
a second frame slidingly arranged on said first frame;
guide means for said second frame with respect to said first frame;
third elastic means to move said second frame away from said first frame;
first thrust means for said plurality of first external sector elements, integrally arranged on said second frame;
second thrust means for, said plurality of second internal sector elements, integrally arranged on said second frame;
a lid supporting element;
means to extract the lid from said lid supporting element, slidingly arranged on the latter; and
actuating elastic means for said extraction means;
the arrangement being such that each time said second frame approaches or moves away with respect to said first frame there is a corresponding mutual movement of said plurality of first and second sector elements orthogonal to the direction of movement of the second frame, such as approaching carrying out a reeding pressure moulding on a lip of a lid inserted between said first and second sector elements, so as to give said lip a reduced perimeter outline apt to allow piling up on other similar lids after extraction of the lid from said lid supporting element.